But, in the event of a Central Powers victory in 1916, what would a violent, uncontrolled break up of the Austro-Hungarian Empire look like and what would be the immediate response of the nations surrounding it (especially Germany)?
To cut it short, with a 1916 victory it probably won't collapse.
Before the war, Austro-Hungary was under extreme strain from the fact that it was a multiculturalist's worst nightmare: it was too ethnically and culturally diverse to exist as a singular nation, mostly due to Austrian mismanagement. For example, there were 15 versions of the national anthem.
While nationalist sentiments certainly were a point of contention I wouldn't call it multicultarist's worst nightmare. There was comparatively little oppression along language lines, let alone violence. The worst affected were the Ruthenians/Ukrainians/Russians (as ill defined as language/national/cultural groups were) and even those were only systematically discriminated against after the Russian war declaration.
Now I won't say that it was all peaceful, but compared to the other Empires of the time it wasn't a negative standout in this regard. Most of the opinion you spout comes from immediate post war historical writing, in an era that gave rise to people like Hitler and where new nations had to justify their own existence.
And I'd even dispute the "Austrian mismanagement". You obviously aim that at the "Germans" as so many people spinning the narrative did. However there were a probably more high ranking officials from Czechia than today's Austria...
15 national anthems? Really? You don't consider the complex government of the double monarchy, internal tolls or the status of Bosnia as important signifier, but the anthem? To cut this down, it was one anthem (per ruler) that was translated into the various languages of the empire. If this hadn't happened you'd complain about "Austrian oppression".
This caused problems in the Austro-Hungarian Army with 80% of their officers being German speakers. In said army, the largest ethnic groups were the Germans and the Hungarians with the rest including Ukrainians, Romanians, Slovaks and Poles making up the rest of the army. Nationalist unrest was rife throughout the army.
Not gonna search for that number. It's either counting proficiency not mother tongue, or it's limited to higher ranking officers in that case it'd be down to class less than origin. Even the Hungarian upper class/nobility/land owners were mostly brought up with German as their first language...
The army was complex and yes there were nationalist problems every now and again. But it's far from as bad as you consider it.
No Croatians and Czechs in the army? I'm surprised, since they actually made up a significant amount compared to the "minor" groups you mentioned.
Just to cut some ideas down. Austria-Hungary did not have a coalition government as we know it today in pretty much every democracy. Issues were dealt with with ad-hoc alliances between the many parties. Most language groups had at least three factions represented in the parliament and the real beauty of it was that the government had to piece together ever changing alliances. No "we have a majority and run all over you". More "I'll help you today if you help me tomorrow". It's probably the best government for compromise.
It comes with drawbacks. Franz Josef every now and then had to override the government if he needed something done fast. Or to be honest, simply disagreed with their ideas. During wartime those emergency rulings became more common. Still parliament continued to meet and this tradition of keeping all options open was kept as well.
So when Czech history writes that the a Bohemian faction was for independence of their country, then there were two other Bohemian factions who were against it...
In 1916 the country was still far from the brink it reached late 1917 or even then 1918. Before that point Austria-Hungary would most likely not have settled down peacefully, but was unlikely to disintegrate. A new Ausgleich would have been fought over a lot. But unless Germany backstabs A-H in a victorious scenario I just can't see it disintegrate in 1916.